PrusaSlicer produces empty layers. Any way around it?  

RE: PrusaSlicer produces empty layers. Any way around it?

If you are usig Windows10,  Right click to select the  part in 3D editor section of Prusa Slicer, then choose Fix with the Netfabb

regards  Joan

RE: PrusaSlicer produces empty layers. Any way around it?

Hi,

I downloaded your "good" version and rotated it like on your screenshot. After slicing, there are no artifacts (also 2.3.0+).

However, the slicer reports 12 errors in this file. You should use "context menu - Fix through the Netfabb". Maybe that resolves your problem.

RE: PrusaSlicer produces empty layers. Any way around it?

OSX version. I don't see this option:

RE: PrusaSlicer produces empty layers. Any way around it?

It looks like saving failing parts as separate 3mf files and reopening them anew fixes the problem.

RE: PrusaSlicer produces empty layers. Any way around it?

Repair with Netfabb is a Windows 10 feature, only. If I remember correctly.

Edit: Yes, only Windows 10: https://help.prusa3d.com/en/article/corrupted-3d-models-for-printing_2205

RE: PrusaSlicer produces empty layers. Any way around it?

@dr-print

I used the STL file from this Thingverse project.

My steps to reproduce the issue in the OSX version:

1. Import the STL mold file FlowerPot7_MoldB.STL into an empty project
2. Rotate the mold on its side
3. Select the mold and cut it into two halves with the "Cut [C]" 3D command
4. Rearrange and rotate back both halves into "vertical" positions
5. Slice

RE: PrusaSlicer produces empty layers. Any way around it?

There’s also a web version of Netfabb at https://service.netfabb.com/login.php .

As the error message says, most likely the model is broken. Plenty of stuff on Thingiverse (and other sites) that have faults. 

RE: PrusaSlicer produces empty layers. Any way around it?

I'm afraid I can't see the issue.  The full pot slices just fine in any position on my PS, which is now 2.3.0

RE: PrusaSlicer produces empty layers. Any way around it?

@jsw

Did you try to cut the pot into two halves and re-slice them?

RE: PrusaSlicer produces empty layers. Any way around it?

Posted by: @sergen

@jsw

Did you try to cut the pot into two halves and re-slice them?

 

Yes, it slices as expected.

RE: PrusaSlicer produces empty layers. Any way around it?

It very consistently fails in my case in Apple OSX 🤷‍♂️ 
(that's why at work we employ MC/DC testing. By the random look of the issue I'd say it's a use of an uninitialized variable)

RE: PrusaSlicer produces empty layers. Any way around it?

Following your instructions, I get the same error (2.3.0+win64):

But the slicer does not show any information that the mesh contains any errors (in contrary to the 3mf file, where PrusaSlicer indicated the problems right away). If I use "Fix through the Netfabb" nevertheless, I pot slices without any errors.

RE: PrusaSlicer produces empty layers. Any way around it?

@dr-print

So the bug is real and only the Windows version has a workaround for it, right?

RE: PrusaSlicer produces empty layers. Any way around it?

No there is an issue with the model.  Its just the the windows version is the only version that has built in access to netfabb.  Even the built in one is using the netfabb servers to do the work.  Its just removing an extra user step.  There are also other methods of fixing models. 

If you intend to continue printing stuff from the internet you will have to learn one or more of them as there are more broken models out there than good ones.  Even designing your own models is not without pitfalls as its very easy to produce something that has issues in ANY of the cad design packages.  At least if its your own design you have the original and can learn to fix it.

RE: PrusaSlicer produces empty layers. Any way around it?

@neophyl

If the model is not cut in half, the slicing goes OK. Hence it's not the model problem, right? It's a logical implication.

RE: PrusaSlicer produces empty layers. Any way around it?

@sergen

Except its not a logical conclusion no.  Cutting a model produces new and different vertices.  These new vertices can actually produce new/different model errors but those errors or the placement of them causes the slicing engine to produce totally different results.  The new errors might be handled ok and so the model slices fine.  They could just as easily lead to slicing problems in different areas.

Its why sometime just rotating a model slightly can also lead to a slice working or not when it did or didn't before.  Or choosing a different layer height.  As the slicer is evaluating layer by layer its working with what it has at that time.  If you have a problematic vertice thats right on the edge of some mathematical algorithm then even a slight change in some maths rounding can produce different results.  Different OS and libraries can also treat math differently, especially anything floating point.

Thats also the reason that sometimes saving the file as a 3mf and then reloading it can work too.  the 3mf format is supposed to be designed to not allow common errors in the data.  Something like stl has zero checks for anything being 'wrong'.

PS is 'ok' at fixing models behind the scenes but its not as good as say Cura with some models.  However every single one of these issues I've seen so far (and I've seen a lot both here and on the github site) has been down to errors within the model of some form or another. 

RE: PrusaSlicer produces empty layers. Any way around it?

As a sanity check, I went back and sliced it with both halves placed on the sheet at the same time, similar to the example above, which has obviously failed.

Again, it sliced as expected and should be printable.

This is using PS 2.3.0 on Ubuntu Linux which was recently updated (??) 😉 to 20.04.

As another sanity check, I sliced both halves with Cura, which is usually my first step when a model refuses to slice properly in PS.  As you will see below, again, it sliced fine.

I don't know what the thing is here.  Usually when someone's reported a .stl which will not slice, I was always able to duplicate the issue, and in some cases to repair it using various tricks.

I went back and confirmed that I'm following the steps you used (rotate, cut, re-rotate) in PS.  The Cura attempt was using exported .stls from the PS attempt.

When I have some time later today I'll try it again using the PC in the office, which is Windows (7 - yes, I know ...) and see what that does.  LOL, I'm not really sure what version of PS is running on that one.

My personal experience is that Cura is often (but not always) more 'forgiving' when it comes to corrupt .stl files posted on the 'usual suspect' 3d sites.  When one comes up with empty spaces in PS, I'll usually try Cura, and often (but not always) it will slice and print as expected.

When I get one that still refuses to slice (the models I typically download, model railroad buildings, tend to be notoriously corrupt for some reason) I'll import it into FreeCAD, convert the mesh to a shape, refine the shape, convert to a solid, and re-export.  I would say I have a 70-80% success rate doing that.  If that fails, I'll usually try the stand-alone Netfabb, and if that fails, MeshLab as a last resort, which maybe has a 40-50% success rate.

That's been my experience anyway.

RE: PrusaSlicer produces empty layers. Any way around it?

I don't know what to tell you here.

This is on the Windows 7 machine.  (It has not been updated due to reports that a couple of applications on it will break on Win 8/10) and I verified that it's running 2.3.0 as well.  As you see, it slices as expected.

RE: PrusaSlicer produces empty layers. Any way around it?

But based on where the defects are in the model, your cut may may or may not produce two broken submodels or not. In any case, I’d file this (as usual) under “broken model”, not “bug in PS”. I’ve made it a habit of running any STLs first through netfabb before I post them to the community.